Faced with a $54.1 million budget gap next year, Mayor Kurt L. Schmoke has asked for reductions in the fiscal 1992 budget requests of three agencies previously spared from cuts -- police, fire and education.

The growing budget crunch also appeared to be spelling an end to the Baltimore Trolley Works; city transportation officials said the service will be shut down and its 61 employees laid off March 1.

Clinton R. Coleman, Schmoke's press secretary, said yesterday that memorandums outlining the reductions were sent to department heads as part of the "annual budget exercise." He also said the proposed cuts were preliminary.

But given the city's budget problems and the slim chance of significant state aid this year, Coleman added: "No agency at this point is likely to be spared reductions."

In the memo, the mayor's budget staff ordered that in making cuts, key personnel and facilities such as classroom teachers, on-the-street firefighters, fire stations, paramedics and police officers be spared.

"I think it's going to have devastating repercussions," said David L. Glenn, president of the Board of Fire Commissioners. "I am sort of confounded and dumbfounded by the memo. We understand the plight of the city. But I just don't understand how you can [make this kind of cut with the mayor's constraints] and maintain the fire system."

In the memo, the budget office said that the Fire Department's budget "target" for the fiscal year beginning July 1 is $96.6 million -- $7.6 million more than the current budget, but about $3.5 million less than the department was counting on.

Schmoke is proposing that the school system, which is funded mostly with state and federal money, get $191.1 million in city funds. That figure is 5.5 percent over the current city contribution, but about $6 million less than was contemplated when the school board passed its proposed $551 million budget earlier this month.

Schmoke also issued a long list of conditions for the education cuts. Among them were mandates that class-size ratios not increase, funds for books and supplies remain at current levels and staff in the schools not be reduced.

The budget target for the Police Department has been set at $178.1 million for fiscal 1992, an increase of $8.9 million, or 5.3 percent, over the current appropriation. The department had asked for about a $13 million increase, Coleman said.

In getting to the mayor's budget target, the department must not reduce the number of police officers nor close any police districts, the memo said.

Edward J. Gallagher, the city budget chief, said this is a "tough year" for Baltimore because of its financial problems. But, he added, no final decision on the budget will be made until April, when the mayor's recommendations go to the Board of Estimates.

In announcing that the trolley system's $500,000 budget could no longer be afforded, Transportation Commissioner Herman Williams Jr. said yesterday that the downtown trolley bus service -- started in 1985 -- was suffering from a lack of advertising revenue and that an eight-month effort to find a private operator for the buses was unsuccessful.